import type { TTSOptions, TTSResult, TTSVoice, TTSHandler } from "../../types/index.js";
export declare class GoogleTTSHandler implements TTSHandler {
    private client;
    private voicesCache;
    private static readonly CACHE_TTL_MS;
    /**
     * Google Cloud TTS maximum input size.
     * ~5000 bytes INCLUDING SSML tags.
     */
    private static readonly DEFAULT_MAX_TEXT_LENGTH;
    /**
     * Default timeout for Google Cloud TTS API calls (milliseconds)
     *
     * Google typically responds within:
     * - 1–5 seconds for short or normal text
     * - 5–10 seconds for longer text or Neural2 voices
     */
    private static readonly DEFAULT_API_TIMEOUT_MS;
    /**
     * Maximum text length supported by Google Cloud TTS (in bytes).
     *
     * NOTE:
     * Validation against this limit is performed by the shared TTS processor
     * before invoking provider handlers, not inside this class.
     */
    readonly maxTextLength: number;
    constructor(credentialsPath?: string);
    /**
     * Validate that the provider is properly configured
     *
     * @returns True if provider can generate TTS
     */
    isConfigured(): boolean;
    /**
     * Get available voices for the provider
     *
     * Note: This method is optional in the TTSHandler interface, but Google Cloud TTS
     * fully implements it to provide comprehensive voice discovery capabilities.
     *
     * @param languageCode - Optional language filter (e.g., "en-US")
     * @returns List of available voices
     */
    getVoices(languageCode?: string): Promise<TTSVoice[]>;
    /**
     * Generate audio from text using provider-specific TTS API
     *
     * @param text - Text or SSML to convert to speech
     * @param options - TTS configuration options
     * @returns Audio buffer with metadata
     */
    synthesize(text: string, options: TTSOptions): Promise<TTSResult>;
    /**
     * Extract language code from a Google Cloud voice name
     *
     * Example:
     *   "en-US-Neural2-C" -> "en-US"
     *
     * @param voiceId - Google Cloud voice identifier
     * @returns Language code compatible with Google TTS
     */
    private extractLanguageCode;
    /**
     * Map application audio format to Google Cloud audio encoding
     *
     * @param format - Audio format requested by the caller
     * @returns Google Cloud AudioEncoding enum value
     * @throws Error if format is unsupported
     */
    private mapFormat;
    /**
     * Detect the voice type from a Google Cloud TTS voice name
     *
     * Parses the voice name to identify the underlying voice technology/model type.
     * Google Cloud TTS offers different voice types with varying quality and pricing.
     *
     * @param name - The full Google Cloud voice name (e.g., "en-US-Neural2-C")
     * @returns The detected voice type
     *
     * @example
     * detectVoiceType("en-US-Neural2-C") // returns "neural"
     * detectVoiceType("en-US-Wavenet-A") // returns "wavenet"
     * detectVoiceType("en-US-Standard-B") // returns "standard"
     * detectVoiceType("en-US-Chirp-A") // returns "chirp"
     * detectVoiceType("en-US-Journey-D") // returns "unknown" (unrecognized type)
     */
    private detectVoiceType;
}